No one has ever doubted that truth and politics are on rather bad terms with each other, and no one, as far as I know, has ever counted truthfulness among the political virtues.

Hannah Arendt, “Truth and Politics” (1967)

I think the pundits are missing the essential point when they simply call Trump a liar.

First of all, it is hardly a disqualifying attribute. We all are liars. Social life is lubricated by lies (“Thank you, Aunt Martha, it’s a beautiful sweater, I love it.”). Most politicians twist and bend the truth to their purpose. Many have been accomplished liars and the accepted script for contemporary political life calls for pretty constant fib and spin, where the question is how far the politician can depart from the “whole truth” without getting into too much trouble (the Clintons being masters of this). And needless to say many 20th century presidents, including those generally considered a success (FDR, JFK, etc.), lied about all sorts of things.

So what is it about Trump and the truth that is different?

Narcissists rarely behave as if truth is some static objective reality. Instead, the typical narcissist regards as “true” (in the sense of “valid”) that which he says and thinks in the moment, that which makes him look good, and that which will get him what he wants. So for Trump, truth is not the way things are, but the way things ought to be given the overriding validity and importance of the narcissist’s narrative about himself (e.g., I’m the most successful person ever, I’m a winner, I alone can solve our problems). Truth is what it needs to be to get him what he wants. This deep conviction allows the narcissist to stray from the truth without conscience or shame, because a small thing like objective reality is nothing compared to the greater truth of the narcissist’s specialness and the overwhelming imperative to fulfill his desires. As a result, narcissists tend to be relaxed and brilliant liars.

This typical narcissistic trait is confirmed by those closest to Trump. Tony Schwartz, the ghostwriter of Art of the Deal, observed that lying seemed to be “second nature” to Trump. He reported, “More than anyone else I have ever met, Trump has the ability to convince himself that whatever he is saying at any given moment is true, or sort of true, or at least ought to be true. . . . He has a complete lack of conscience about it.” When confronted with opposing facts, Schwartz said that Trump would double down, repeat himself, and grow belligerent. Schwartz observed this in the mid-1980s and nothing has changed. All of us have observed this pattern repeatedly over the course of the campaign. (See, for example, the transcript of Trump’s radio interview with conservative talk show host Hugh Hewitt, who helpfully suggested that perhaps his Obama-as-founder-of-ISIS remarks were metaphorical. “No, I meant he’s the founder of ISIS,” Trump replied. “But . . . he’s trying to kill them,” the host pushed back. “I don’t care. He was the founder.”)

This core narcissistic trait explains how Trump is able repeatedly to assert the manifestly untrue with enormous conviction and without any of the ticks or signs of embarrassment the rest of us exhibit when lying. It explains how he was able to drift into the dark waters of the birther crackpots and remain impervious to mountains of contrary evidence. The Economist called him “the leading exponent of ‘post-truth’ politics – a reliance on assertions that ‘feel true’ but have no basis in fact.”

In the case of ordinary politicians in a democracy, the lie is a mainly defensive tool, used only occasionally to hide or deny conduct or circumstances that would be embarrassing or inexpedient. But without conscience or even an underlying preference for objective truth, Trump’s rhetoric drifts constantly between the real and the fictional. When Politico reporters fact-checked 4.6 hours of Trump speeches and press conferences, they found more than five dozen untrue statements, or one every five minutes.

So, crippled by a real disability in relation to truth telling, why has Trump prospered? The great chronicler of 20th century authoritarianism, Hannah Arendt, would not be surprised: “Since the liar is free to fashion his ‘facts’ to fit the profit and pleasure, or even the mere expectations, of his audience, the chances are that he will be more persuasive than the truth teller [emphasis added].” She also observed that in a democracy (i.e., before belief in lies is enforced by an authoritarian state), “deception without self-deception is well-nigh impossible” (i.e., for the liar to succeed, his audiences need to embrace the lies voluntarily). If you doubt the truth of Arendt’s observations, watch and listen to the New York Time’s video compilation of Trump rally audiences here.

So does Trump’s unique disdain for the value of objective truth matter? The answer is yes, it matters a lot. This is because respect for objective truth, and a broad social agreement that politicians and policies can and should be judged by how far they stray from it, is one of our prime defenses against authoritarianism (either of the right or of the left). Hannah Arendt pointed out that in the 20th century authoritarians were more hostile to facts that were inconsistent with their core narratives than they were to opposing political opinions. And one of the turning points on the road to authoritarianism was when objective reality (e.g., Obama’s birthplace or the greenhouse effect) was undermined to become a mere matter of political opinion. So yes, politicians have always lied. But a generalized disdain for objective reality in favor of the “greater truth” of the egomaniacal strongman is the core of what Tom Friedman called “the moral and civic cancer that Trump has [been] injecting into the body politic.”